Coating of fabrics



Patented Oct. 7 27, 1953 COATING OF FABRICS Herbert Gensel,.LeverkusemWiesdor-f, and Erwin Windemuth, Leverkusen-Bayerwerk,Germany, assignors to Farbenfabriken Bayer Aktiengesellschaft,Leverkusen, Germany, a corporation of Germany No Drawing.

Application June 21, 1950, Serial No. 169,522. In Germany September 23,1949 10 Claims.

The present invention relates to the coating of fabrics and moreparticularly to a process whereby the fabrics are coated with isocyanatemodified polyesters or with mixtures of polyesters and diisocyanates.

It is known to produce polymers by reacting polyesters withdiisocyanates, which polymers are of more or less elastic characterdepending upon the kind of polyester used. as a starting material. It isfurthermore known to apply mixtures of polyesters and diisocyanates tovarious surfaces, hard or soft or even rubber-elastic coatings beingobtained depending upon the nature of starting material employed. It hasalso been proposed to employ such products for the impregnation oftextile materials.

All attempts to utilize the excellent properties of these polymers forthe coating of fabrics, for instance for the production of rain coatsand the like, have had no practical result. This is due to the fact thatthe components, viz. the diisocyanate modified polyesters or thepolyesters on the one hand and the diisocyanates on the other can onlybe distributed on the fabrics in the form of their solutions in organicsolvents. These solutions penetrate the textiles so farthat they I areimpregnated throughout and thus lose their textile character. It istherefore impossible to coat the textiles with the polymers only on oneside, that is to retain the textile character thereof on one side, suchas is necessary for many rubber impregnated articles.

It is therefore an object of the invention to provide a process by whichfabrics and other textile materials may be coated on one side only witha synthetic elastomer.

A.- further object resides in the provision of ing the textiles to becoated with water or an aqueous solution of analipha-tic diamine oramino alcohol, then coating said textiles in the moist state with asolution or emulsion of polyesters and di-isocyanatesor of theirconversion products,

or an aqueous gsolution of a diamine.

If the pretreatment of the fabric to be coated is carried out withwater, the textile material should contain about -100 per cent of itsweight of water, in order to prevent the coating solution frompenetrating through the fabric. If instead, of water, an aqueoussolution of aliphatic diamines, especially ethylene diamine or aminoalcohols such as diethanolamine, is used, a moisture content of 5-10 percent of the weight of the fabric is sufficient and up to about 50 percent may conveniently be employed.

By this pretreatment the undesirably deep penetration of the polymersolution into the fabric is avoided, and a rapid condensation of thepolymer brought about. It is then only necessary to remove the excesswater and to complete the reaction of the diisocyanate with thepolyester and of the soluble isocyanate modified polyester with water oramine.

As starting materials for the coating of fabrics, especially such'isocyanate modified polyesters are suitable, which are still soluble inorganic solvents. As polyesters, polyesters from adipic acid anddiethylene glycol and other polyglycols are preferred. Furthermore,polyesters from adipic acid and 1,2-propylene glycol, thiodiglycol,quim'te and others may be used. As-acid components, other dicarboxylicacids than adipic acid such as sebacic acid, thiodibutyric acid, maleicacid'and phthalic acid may be employed. Hydroxycarboxylic acids may alsobe employed for the production of the polyester. It is advisable toemploy an excess of glycol, which excess causes the end groups of thepolyester to consist mainly of hydroxyl groups, while free carboxylgroups occur only to a small degree.

Such polyesters are reacted with organic diisocyanates and then containas reactive groups mainly isocyanate groups. For this reactiondiisocyanates are suitable such as tetramethylene diisocyanate,hexamethylene diisocyanate, dodecamethylene diisocyanate, cyclohexanediisocyanate, dicyclohexylmethane diisocyanate, thiodipropyldiisoc-yanate, toluylene diisocyanate and others.

If, instead of 'isocyanate modified polyesters combinations ofpolyesters with diisocyanates are employed, which have not yet or onlypartly reacted with each other, polyhydroxy compounds with threehydroxyl groups, such as glycerol, hexanetriol, trimethylolpropane, etc.may be employed, besides the dihydroxyl compounds enumerated. v

'As solvents for the combination of polyesters and diisocyanates or forthe isocyanate modified polyesters, organic solvents free from hydroxylgroups such as benzene, methylglycolacetate, ethyl acetate and the likeor mixtures of these compounds may be employed. Naturally, care shouldbe taken that the organic solvent does not destroy the fiber, whichwould be possible if cellulose acetate were employed in the fabric.Aqueous emulsions of isocyanate modified polyesters may also be used.The liquid coating medium preferably contains at least 50 per cent ofits weight of the isocyanate modified polyester.

The reaction between the isocyanate groups and water or amine may besubstantially accelerated by adding about 0.1-2 per cent of tertiaryamines like dimethylaminocyclohexane, dimethylpiperazine,perhydroethylcarbazole, methylor butylpyrrolidine or trialliylamines.

In many cases it is advisable to treat the coated fabric, afterdistributing the solution thereon, with the vapor of an aliphaticdiamine especially ethylene diamine. Thus a rapid cross-linking of thepolymer on the coated side of the fabric is brought about. Thisaftertreatment may also be employed in order to deluster the surface ofthe coating. If the aftertreatment is not carried out, in contrastthereto shiny coatings having the appearance of lacquers are obtained.Instead of using the diamine in vapor form, it is also possible toemploy it in solution for the aftertreatmerit.

The coated fabrics of this invention are suitable for all purposes forwhich rubber coated fabrics have hitherto been employed, for instancefor rain coats, oil cloth, water resistant chintz and the like. Theprocess is also suitable for the production of multilayer fabrics suchas are for instance employed for automobile tops. In this casepretreatment of the fabric as well as the aftertreatment necessary forcross-linking is carried out in such a manner, that the fabric is soakedin an aqueous solution of ethylenediamine, two lengths of fabric arecoated on one sideonly, the layers united on the coated side, andsubsequently dried in the heat. By the pretreatment with the solution ofdiamine the penetration of the coating solution to the uncoated side ofthe fabric is prevented, while drying in the heat results incross-linking of the isocyanate modified polyesters by means or theethylene diamine and water vapour. The isocyanate modified polyester isthus solidified.

The process also be employed for the coating of filaments. V In thiscase the filament is surrounded without being impregnated. Filaments ofthis kind may be used as substitutes for violin strings, wicker worketc.

The present invention is illustrated by the following examples withoutbeing restricted thereto:

Example 1 Cotton poplin fabric is treated with water on the foulard, anddried on a calender until the residual moisture is about 80 per cent ofthe fabric weight. The pretreated fabric is then coated with a coatingmixture consisting of an 30 per cent solution of an adipic aciddiethylene glycol polyester having a hydroxyl number of 65 and an acidnumber of about 0.1, and 15 per cent of the weight of the polyester oftoluylene diisocyanate. The fabric is subsequently led through a chambersaturated with ethylene diamine vapor. This process may be repeateduntil the coating has the desired thickness. Finally the fabric iswashed on a jigger with a solution of about 10 com. of acetic acid inone liter of water and dried. A watertight poplin suitable for theproduction of rain coats is obtained in this manner, which is coated onone side only.

Example 2 A fabric of viscose taffeta is treated on a foulard with a 10per cent aqueous solution of ethylenediamine and subsequently dried to aresidual water content of about 30 per cent of the fabric weight. Thefabric thus pretreated is coated on one side in a coating machine with acoating mix ture obtained from a '70 per cent solution in benzene of anadipic acid diethyleneglycol polyester having an hydroxyl number of 55and an acid number of 1.5, and 11 per cent of the weight of thepolyester of hexamethylenediisocyanate. The fabric is further treated asindicated in Example 1 and finally impregnated with one of the knownwater repelling agents, for instance a parafiin emulsion of an aluminiumsalt. In this manner a viscose taffeta suitable as rain coat material,which is water tight and water repellent, is obtained.

Example 3 A taffeta fabric from acetate rayon is treated on a foulardwith a 5 per cent aqueous solution of ethylene diamine and subsequentlydried to a residual water content of about 10 per cent. The mixtureemployed for coating is obtained by reacting 100 parts of an adipic aciddiethylene glycol polyester having a hydroxyl number of 33.4 and an acidnumber of 1.1 with 10.6 parts of l,6-cyclohexanediisocyanate. Thecoating mixture is employed as an per cent solution in benzene. Aftereach coating the coated side of the fabric is treated with an aqueoussolution of ethylenediamine and dried. The fabric is first washed withwater as indicated in Example 2 and then treated with an agent impartingwater repellent properties. In this manner a rain coat material isobtained, which is water tight and water repellent.

Example 4 A cotton'poplin fabric is treated on a foulard with a solutioncontaining per liter of water 20 grams of diethanolamine and 10 grams ofhexahydrodimethylaniline as a catalyst. The fabric is dried to aresidual moisture content of about 10 per cent of water. The fabric isthen coated with the coating mixture as described in Example 2 and ledfor a short period through a chamber saturated with the vapor ofethylenediamine.

Finally the fabric is finished as indicated in Example 2.

Example 5 A canvas consisting of cotton and warp linen is treated on afoulard with a ten per cent aqueous solution of ethylene diamine. Twowidths are made of the fabric and each of the widths coated on a liningmachine with an 80 per cent solution of a coating mixture of the samecomposition as in Example 2. The Widths are then united with theircoated sides in suitable manner and dried hot under pressure. In thismanner a solid adhesion of the two widths results.

Example 6 A taffeta fabric of cupramrnonia rayon is treated on a foulardwith a ten per cent aqueous tion:

solution of hexamethylene diamine and subsequently dried to a residualmoisture content of about per cent. The pretreated fabric is then coatedfour times, each coating being dried at 140 C. with a coating of thefollowing composi- 100 parts of the polyester from three mols of adipicacid, one mol of hexane trio] and three mols of butylene glycol,

36 parts of toluylene diisocyanate, and

10 parts of butylacetate.

Finally the fabric is washed on a jigger with a 3 per cent acetic acidsolution, rinsed, and dried. In this manner a fabric coated on one sideonly With a coating having a high luster is obtained.

Example 7 A viscose rayon taffeta fabric is treated on a foulardwith afive per cent aqueous solution of ethylene diamine and then dried to aresidual moisture content of about 5 per cent. The pretreated fabric iscoated three times with a coating of the following composition, eachcoating being dried at 140 C.:

100 parts of polyester from three mols of adipic acid, two mols oftrimethylolpropane and two mols of butyleneglycol,

36 parts of hexanediisocyanate, and

10 parts of butylacetate.

The fabric is then coated again and immediately afterwards led through achamber saturated with ethylene diamine vapor. Finally the fabric iswashed with a 3 per cent acetic acid solution, rinsed, and dried. Afabric coated on one side having a delustered appearance is obtained.

Example 8 6.5 parts of a condensation product from xylene andformaldehyde, said condensation product being hydroxyethylated by meansof ethylene oxide, are dissolved in 12.5 parts of water, and 130 partsof the coating composition as described in Example 2 are emulsified inthis solution by gradual addition with stirring. The 50 per centemulsion obtained in this manner is coated on a cotton taffeta fabricpretreated with a 5 per cent aqueous ethylene diamine solution, andfinally aftertreated with ethylene diamine vapor. In this manner afabric is obtained coated on one side and having a rubbery hand.

We claim:

1. A process of coating textiles which comprises impregnating saidtextiles with an aqueous medium of the group consisting of water, anaqueous solution of an aliphatic diamine and an aqueous solution of analiphatic amino-alcohol, coating the impregnated textiles with a liquidmedium containing an isocyanate modified polyester that is still solublein organic solvents and whose sole reactive groups are isocyanategroups, said aqueous impregnating medium being present in said textilesin an amount sufficient to prevent substantial penetration of saidliquid coating medium therein, and effecting cross-linking of saidisocyanate modified polyester by treating said coated textiles with across-linking agent.

2. A process as claimed in claim 1 wherein the aqueous impregnatingmedium is water and. the

impregnated textiles are dried to a moisture content of from about toabout per cent before applying the liquid coating medium.

3. A process as claimed in claim 1 wherein the aqueous impregnatingmedium is an aqueous solution of an aliphatic diamine and theimpregnated textiles are dried to a moisture content of from about 5 toabout 50 per cent before applying the liquid coating medium.

4. A process as claimed in claim 1 wherein the aqueous impregnatingmedium is an aqueous solution of an aliphatic amino alcohol and theimpregnated textiles are dried to a moisture content of from about 5 toabout 50 per cent before applying the liquid coating medium.

5. A process as claimed in claim 1 wherein the coated textiles aretreated with the vapor of a cross-linking agent of the group consistingof water and an aliphatic diamine to effect crosslinking of theisocyanate modified polyester.

6. A process of coating textiles which comprises impregnating saidtextiles With an aqueous medium of the group consisting of water, anaqueous solution of an aliphatic diamine and an aqueous solution of analiphatic amino-alcohol, coating the impregnated textiles on one sideonly with a liquid medium containing at least 50 per cent of anisocyanate modified polyester that is still soluble in organic solventsand whose sole reactive groups are isocyanate groups, said aqueousimpregnating medium being present in said textiles in an amountsufficient to prevent substantial penetration of said liquid coatingmedium therein, and treating said coated textiles with the vapor of across-linking agent of the group consisting of water and an aliphaticdiamine to effect cross-linking of the isocyanate modified polyester.

7. A process as claimed in claim 6 wherein the liquid coating-medium isa solution of the iso cyanate modified polyester in an hydroxyl-freeorganic solvent.

8. A process as claimed in claim 6 wherein the liquid coating medium isan aqueous emulsion of the isocyanate modified polyester.

9. A process as claimed in claim 6 wherein the liquid coating mediumcontains from about 0.1 per cent to about 2 per cent of a tertiary aminecalculated on the weight of the isocyanate modified polyester.

10. A process as claimed in claim 6 wherein the isocyanate modifiedpolyester is obtained by mixing an adipic acid diethyleneglycolpolyester having a low acid number with an organic diisocyanate.

HERBERT GEN SEL. ERWIN WINDEMU TH References Cited in the file of thispatent UNITED STATES PATENTS Number Name Date 2,121,717 Sullivan June21, 1938 2,333,639 Christ et a1. Nov. 9, 1943 2,468,713 ropa et al Apr.26, 1949 OTHER REFERENCES Ser. No. 397,741, Schlack (A. P. 0.),published Apr. 20, 1943.

1. A PROCESS OF COATING TEXTILES WHICH COMPRISES IMPREGNATING SAIDTEXTILES WITH AN AQUEOUS MEDIUM OF THE GROUP CONSISTING OF WATER, ANAQUEOUS SOLUTION OF AN ALIPHATIC DIAMINE AND AN AQUEOUS SOLUTION OF ANALIPHATIC AMINO-ALCOHOL, COATING THE IMPREGNATED TEXTILES WITH A LIQUIDMEDIUM CONTAINING AN ISOCYANATE MODIFIED POLYESTER THAT IS STILL SOLUBLEIN ORGANIC SOLVENTS AND WHOSE SOLE REACTIVE GROUPS ARE ISOCYANATEGROUPS, SAID AQUEOUS IMPREGNATING MEDIUM BEING PRESENT IN SAID TEXTILESIN AN AMOUNT SUFFICIENT TO PREVENT SUBSTANTIAL PENETRATION OF SAIDLIQUID COATING MEDIUM THEREIN, AND EFFECTING CROSS-LINKING OF SAIDISOCYANATE MODIFIED POLYESTER BY TREATING SAID COATED TEXTILES WITH ACROSS-LINKING AGENT.